Melhoramento genético para altos teores de ferro e zinco em feijoeiro-comum

• Autor(a) principal: Di Prado, Poliana Regina Carloni
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/7294
• topic: Phaseolus vulgaris L.; Biofortificação; Dialelo; Interação de genótipos com ambientes; Marcadores moleculares; Phaseolus vulgaris L.; Biofortification; Diallel; Genotypes by environments interaction; Molecular markers; FITOTECNIA::MELHORAMENTO VEGETAL

The iron and zinc deficiency reaches millions of people worldwide, generating public health problems. One of the most viable alternatives to minimize this issue is the biofortification and the common bean stands out as a crop with wide potential to be biofortified. The objectives of this work were: i) to verify the importance of genetic (G), environmental (E) and G x E interaction effects for iron content (FeC) and zinc content (ZnC) in common bean grains and to identify the cultivars/lines that associate high potential for FeC, ZnC, protein content (PtC), yield and weight of 100 grains (W100); ii) to verify if exists genetic relation between these traits; iii) to obtain, evaluate and select promising common bean segregating populations for high FeC and ZnC, yield and W100; iv) to estimate parental general (GCA) and specific (SCA) combining ability for FeC and ZnC, aiming the understanding of genetic control and the selection of parental lines; v) to estimate genetic parameters and to select lines for FeC, ZnC, yield and W100; vi) to validate microsatellites molecular markers (SSR), previously identified as linked to QTLs for FeC and ZnC in common bean, in breeding populations, with high mean. On the first study, to verify the importance of G x E interaction, 34 genotypes were evaluated at 19 environments, assessing the FeC, ZnC, PtC, yield and W100. Combined analyses of variance, adaptability and stability analyses by Nunes graphical method were performed, in addition to the estimation of genetic correlations between the traits. There were significant differences between genotypes for all traits. The environment and interaction effects were significant, and the environment represented the most of total variation, 63% (FeC) and 65% (ZnC), followed by G x E interaction effect, 18% (FeC) and 15% (ZnC). The cultivar BRS Sublime, with carioca grains type, combined high FeC, ZnC, PtC, yield and grains with commercial size, in addition to wide adaptability and stability. The genetic correlations between FeC x ZnC, FeC x PtC and ZnC x PtC were significant and positive, indicating, likely, the occurrence of pleiotropy or that some genes that control these traits are linked. It is concluded that, due to the great environmental effect influencing FeC and ZnC the evaluation trials of these traits should be performed in multiple environments. On the second study, 15 segregating populations were obtained and evaluated from crosses on complete diallel design between six parental lines selected for high FeC and ZnC. The populations were assessed at Santo Antônio de Goiás-GO, on winter/2012 (F2), winter/2013 (F3) and rainy/2013 (F4) seasons, and at Brasília-DF, on rainy/2013 (F4) season. The traits evaluated were FeC and ZnC, yield and W100. Significant differences were detected between the populations for all traits. Based on the combine analysis, for FeC additive effects were more important and the line G 2358 stood out by its high GCA (5.63). For ZnC, both additive and non additive effects were important, however no parental line showed significant GCA. The populations selected simultaneously for all four traits, based on combined analysis, were Porto Real x G 2358, BRSMG Majestoso x G 2358, BRS Requinte x BRSMG Majestoso, Porto Real x BRS Requinte and Porto Real x BRSMG Majestoso. The population BRS Requinte x G 2358 is indicated for extraction of lines with high FeC and ZnC. It is concluded that the parental G 2358 has great potential and must be used in new crosses to increase FeC in common bean grains. The population BRS Requinte x G 2358, that presented excellent performance for FeC and ZnC, and the population BRS Requinte x Porto Real, selected simultaneously for all traits, must follow on the breeding program for lines extraction. On the third step of this work, 116 lines of these two populations and five controls were assessed, in a triple lattice experimental design 11x11, at three environments and FeC, ZnC, yield and W100 were evaluated. Analyses of variance and the estimation of genetic parameters were performed. It was also performed the genotyping of the parental lines and lines of these populations with 20 SSR previously identified as linked to FeC and ZnC QTLs and, later, it was performed the single marker mapping analysis. Differences were identified between the lines at all environments for all traits. The estimates of heritability and expected gain from selection indicated the possibility of obtaining genetic gains for each trait individually. On simultaneous selection of lines for the four traits, based on combined analysis, the expected gains from selection of the best 24 lines were 4.7% for FeC, 2.8% for ZnC, 3.9% for yield and 0.9% for W100. Only the marker BM 154 was polymorphic and only on population BRS Requinte x Porto Real. The single marker mapping analysis showed association only between BM 154 and FeC, at one environment, explaining 14.5% of the phenotypic variation. It is concluded that there is possibility on selecting lines that combine desired phenotypes for the four traits of interest and that, likely, the QTLs linked to the tested markers are already fixed and that there is the presence of QTLs x environments interaction.